Swash plate mechanism for engines



Feb. 27, 1934. Q Bl REDRUP 1,948,827

SWASH PLATE MECHANISM FOR ENGINES Filed March 17, 195.5 2 Sheets-Sheet 1 //MV dwf Feb.` 27, 1934. c. B. REDRUP SWASH PLATE MECHANISM FOR ENGINES 2 Sheets-Sheet 2 Filed March 17, 1935 Patented Feb. 27, 1934 1,948,827

UNITED" STATES PATENT OFFICE 1,948,827 SWASH PLATE MECHANISM FOR ENGINES Charles Benjamin Redrup, Bristol, England, as-

signor to The Bristol Tramways & Carriage Company Limited, Bristol, England, a British company Application March 17, 1933, Serial No. l661,398 In Great BritainMarch 18, 1932 7 Claims. (Cl. 'I4-14) This invention is for improvements in or relaton the swash member should approximate as ing to internal-combustion and other engines of nearly as possible to the general expressionl the kind wherein the engine connecting rods are 2 2 2 articulately connected to a swash member `which y2=5-(2E-n 0:fl

5 is so mounted on the engine shaft that relative R (1l-Cos a) 60 rotation between these two latter parts takes place `Where It and y are rectangular Coordinates. 0 1S about an axis inclined to the engine shaft, and the angle the inclined axis makes with the engine which swash member is so anchored to a part of Shaft and R iS the perpendicular diStanee Of the the engine that substantial rotational movement point in question from the Saidinelned aXS. It

of the swash member as a whole relatively to the will be appreciated that the path of movement of e5 engine cylinders about the engine shaft is prethe IJOintleS Ontbe Surface 0f a Sphere 0f radius vented. The above mentioned anchorage is re- R andthe eXDreSSiOn given abOVe applieS t0 the quired in order that the connecting rods of the prOJ'eCtiOn 0f the path 0f lnOVeInent 0n t0 a Plane engine may be constrained to move in definite tangential to the said sphere at the pointk at which in paths. Heretofore, the anchorage has been efthe heure-ofreght crosses itself. Thus, if any 70A fected mainly in two ways; the swash member has one point on a plane transverse to the inclined been carried on trunnions which extend at right axis and passing through the intersection of the angles to the engine shaft, and which are so Seinclined axis and the engine shaft is constrained cured to the engine frame as tofberotatable as a t0 move ina Path according t0 the above expres- ?.0' Whole about an axis at right angles both to the SiOn, all Other points 0n the SWaSh member Will 75' trunnion axis and to the engine shaft. secondly, move in paths of the same shape and proportions an abutment on the swash member has been arbut of different dimensions according to their ranged to travel between guide plates in a, direc.. distance from the said inclined axis; at equal distion backwards and fgrwardg gierig-'the axis 0f tances, the dimensions of the paths are the same.

the engine shaft.' Although these arrangements It will be appreciated, however, that slight e0 had the effect of constraining the connecting rods devlatOnS from this expression Can be made e to move in denite paths, the path of each rod Without Substantially-altering the paths 0f movewhere it was connected to the swash member difment Of the enheeting rOdS; thus, mechanisms fered substantially from the paths of the other Can be employed giving aDDrOXmatOnS 0f the l0 connecting rods. Thus, a balancing of the en.. theoretically required movements. 35

gine could not be effectively brought about. In applying the invention to a swash plate An object of the present invention is to conmechanism in which the swash member is carstrain the connecting rods to move in similar Tied by trllnnlOnS ln the manner described abOVe, paths. In analyzing the paths of movement of a feature of the invention consists in that the different points on the swash member equidistant trunnion axis is given two complete oscillations from said inclined axis, in the two known arrangeabout said inclined axis for each engine revoluments `referred to above, it will be found that tion to such an extent as to the ligure-Of-eight whereas those points which lie on the trunnion movement referred t0 above.

axis in the one construction, andthose which lie In applying the invention to a swash plate in a plane vcontaining the engine shaft and the" mechanism in which the trunnions are formed guideways in the other construction, move in .on an anchor member having a tail-piece mountarcuate paths, those which are disposed at 90 ed in a bearing, the bearing is oscillated. For

to the above mentioned path on the swash memexample, the oscillation may be eiected by an 5 ber move in flgures-of-eight. eccentric driven'V at twice engine speed, in which According to this invention, swash plate mechcase a collar. at one end of the link is arranged anism for internal-combustion and other engines to surround said eccentric, while the other end oi the kind described is characterized in that of said link is connected by a universal joint to means are provided for constraining the swash said bearing. It is usually convenient for the 50 member to move so that all points on a plane oscillation to be effected in a direction transverse transverse to the inclined axis and passing to the engine shaft in a plane at right angles through the intersection oi the inclined axis and thereto. In such an arrangement, the angle the engine shaft trace paths of similar lemniscate through which the trunnion axis is swung should or iigure-of-eght form. be approximately 10.34% oi an angle between 55 Theoretically, the movement of any one point the engine shaft and the aforesaid inclined axis, no

in order that an approximation to the above expression may be obtained.

Another constructional form of the invention consists in that one or more abutments fixed to the swash plate is, or are, engaged by a cam surface or surfaces shaped in the manner of a figure-of-eight as described above. For example, one abutment on the swash member might-be arranged to be engaged by an S-shaped cam surface representing one half of a lgure-of-eight, While another abutment on the opposite end of a diameter of the swash member might be engaged by a complementary S-shaped cam face representing the other half of the gure-of-eight.

The following is a description of an embodiment of the invention as applied to a swash plate type of internal combustion engine, reference being made to the accompanying drawings, in which- Figure 1 is a cross-section through a part of the engine along a plane containing the engine shaft;

Figure 2 is a detail view illustrating one form of mechanism for oscillating the swash member about the crank-pin;

Figure 3 illustrates another form of mechanism for oscillating the swash member;

Figure 4 is a similar view to Figure 1 showing cam means for constraining the swash member to follow the required movement; and

The engine comprises a number of cylinders 20 disposed around a crank-shaft '7 with their axes parallel thereto. The crank-shaft is provided with an inclined crank-pin 21 on which is mounted a swash member 22. The swash member is provided with a number of lugs 23 around its periphery to which are secured by universal joints 24 the engine connecting rods 25. The swash member is hollow and has two bearing sockets formed on opposite sides of a diameter which extends at right angles to the axis of the engine crank-shaft, and through the centre of the crank-pin. An anchor member 3 is arranged to extend through a slot in the swash member into the hollow interior and is provided at its upper end with trunnons 26 which engage said bearing sockets. The anchor member is provided with a cylindrical tail piece 27 which is carried by a bearing 15, and is provided with a locating head 16. The lower part of the bearing is provided with an external part spherical surface 14 which is mounted in a part spherical socket in a carrier 29. Assuming that the carrier 29 is stationary (which it is not) upon the rotation of the crank-shaft it will be found that the anchor member is oscillated about its longitudinal axis and thus the ends of trunnions 26 trace arcuate paths as do also those lugs 23 of the swash plate which lie on or near the trunnion axis, while those lugs at right angles, viz. at the top and bottom of the swash plate trace igures-of-eight. Thus, different connecting rods under such conditions trace different paths. In order to equalize the paths, the tail-piece is given two complete oscillations for each revolution of the crankshaft in a direction transverse to the axis of the crank-shaft, whereby the trunnions and the lugs in line therewith are caused to trace a gure-ofeight. At the same time the width of the figure- .of-eight traced by the upper and lower lugs is reduced and by suitably selecting the degree of oscillation of the tail-piece, the various lugs and thus the end of the connecting rods may be made to trace approximately the same form of path. It is found in practice that the angular extent of oscillation of the crown member iS about 10.34 per cent of the crank angle. In the engine shown in the drawings, the crank angle is 221/2 and the extent of oscillation is 2.42".

The drawings show the anchor member in the mid-point of its oscillation with its axis at right angles to that of the crank-shaft and during one revolution of the crank-shaft it is twice oscillated on either side of this position.

One form of mechanism for oscillating the carrier 29 is shown in Figure 2 and comprises an eccentric 5 which is surrounded by a collar at one end of a link member 2, the other end of which supports said carrier. The eccentric is driven from the crank-shaft by gear wheels 8, 9, 10 and 30 at twice crank-shaft speed, the throw of eccentric being suicient to impart the required angular movement to the anchor member 3.

The mechanism shown in Figure 3 differs mainly in that the eccentric is driven by a chain 11 and sprocket wheels 12 and 13.

As indicated earlier in the specification, if any one part of the swash member is constrained to move in a particular form of path, all other points will move in substantially the same form of path. In the construction shown diagrammatically in Figures 4 and 5, instead of the movement of the swash member being controlled by an anchor member which is oscillated, it is constrained to move in the required manner by rollers 31 secured thereon which engage suitably shaped cam plates 32.

It will be appreciated that it would be dilcult to arrange a roller to follow a cam plate in the complete form of a figure-of-eight, but this is unnecessary if more than one cam plate and one follower is used. In considering the path of movement of points disposed at ninety degrees apart on the swash member, While one point is traversing the curved end portions of the figure-ofeight, the other point at ninety degrees is traversing the cross-over parts of the flgure-of-eight. From this it follows that the complete motion can be obtained by arranging a pair of cam plates opposite one another in each of two positions disposed ninety degrees apart, each pair comprising opposed concave surfaces at the ends of the figure-of-eight. These can best be seen inthe dotted lines in Figure 4. The corresponding pair of cam plates are shown in part section attached to the engine casing at the top of the drawings.

JJhe gure-of-eight shown in chain line 33 represents the path followed by the centre of the roller 31, and has an exaggerated width, the length should be about ten times the width in the proper proportions.

I claim:-

1. A swash plate mechanism for an engine having pistons, a crank shaft with an inclined crank pin, a swash plate rotatably mounted on the crank pin, actuating connections between the pistons and the swash plate, and means for moving the swash plate when the engine is in operation, which means causes each of the actuating connections between the pistons and the swash plate to follow substantially similar paths.

2. A swash -plate mechanism for an engine having pistons, a crank shaft with an inclined crank-pin, a swash member rotatably mounted on the crank-pin, actuating connections between the pistons and the swash member, means for controlling the movement of the swash member, and means for actuating said controlling means when the engine is in operation to cause each of the actuating connections between the pistons lill@ land the swash member to follow substantially similar paths.

3. A swash plate mechanism for an engine having pistons, a crank shaft with an inclined crankpin, a swash member rotatably mounted on the crank-pin, driving connections between the pistons and the swash member, means for controlling the movement of the swash" member, and means for moving the controlling means in timed relation to the crank shaft to equalize the paths of movements of the driving connections between the pistons and the swash member.

4. A swash plate mechanism for an engine having pistons, a crank shaft with an inclined crank-pin, a swash member rotatably mounted on the crank pin, actuating connections between the pistons and the swash member, means for controlling the movement of the swash member, and means for'actuating said controlling means when the engine is in operation to cause each of the actuating connections between the pistons and the swash member to follow paths of the gure-of-eight form.

5. A swash plate mechanism for an engine having pistons, a crank shaft with an inclined crank-pin, a swash plate rotatably mounted on the crank-pin, actuating connections between the pistons and the swash plate, and cam means for moving the swash plate, which cam means causes each of thefactuating connections between the pistons andthe swash plate to follow paths o1' similar gure-of-eight form.

6. A swash plate mechanism for an engine having pistons, a crank shaft with an inclined crankpin, a swash member rotatably mounted on the crank-pin, driving connections between the pistons and the swash member, means for controlling the movement of the the swash member, and gearing connecting the crank shaft to the controlling means for moving the controlling means in timed relation to the crank shaft to equalize the paths of movements of the driving connections between the pistons and the swash member.

7. A swash .plate mechanism for an engine .having pistons, a crankshaft with an inclined crank-pin, a swash member rotatably mounted on the crank-pin, actuating connections between the pistons and the swash member, means for controlling the movement of the swash member, and gearing connecting the crank shaft to the controllingvmeans for actuating said controlling means to cause each of the actuating connections between the pistons and the swash member to follow paths of the figure-of-eight form.

, CHARLES BENJAMIN REDRUP. 

